Current cigarette packages are designed to protect cigarettes from the atmosphere and humidity in order to maintain freshness of the product. These packages include three different wrappings; an interior foil inner liner folded around the cigarettes, which is not sealed; a soft or hard paper or paperboard package; and a sealed transparent exterior overwrap which is typically composed of so-called oriented polypropylene which may consist of a heat-seal modified oriented polypropylene; acrylic heat-seal coated polypropylene or a coextruded ABA type film wherein the A layers are fusion heat sealable polypropylene/polyethylene copolymer and the B layer is oriented homopolymer of polypropylene.
Under normal climatic conditions and assuming a normal shelf life, the current packages maintain satisfactory freshness of cigarettes. However, when stored under various hot and/or dry conditions or for long periods of time, the package structure can be inadequate to protect freshness of cigarettes. In addition, the cigarettes and other smoking articles of the type disclosed in U.S. patent application Ser. No. 650,604 to Sensabaugh et al, and U.S. patent application Ser. No. 791,721, filed Oct. 28, 1985, to Clearman et al, and assigned to present assignee, are substantially more sensitive to moisture than current cigarettes. The preferred cigarette embodiments described in the aforesaid Clearman U.S. patent application produce a smoke-like aerosol from an aerosol forming material. In some instances, the aerosol former can be a hygroscopic material and the sorption of water by the aerosol former is functionally undesirable.
Various packaging overwraps and inner liners have been proposed for improving the barrier properties of current cigarette packages. For example, U.S. Pat. No. 3,948,389 to Molins et al discloses an air impervious inner liner for a cigarette package wherein an air impervious tube is sealed flat with the resulting margin and triangulated ends being folded against the packet. Because of an unusual end flap structure, the packages cannot be sealed by current cigarette manufacturing equipment.
U.S. Pat. No. 4,375,260 to Focke et al discloses a laminated foil inner liner which, as with the above Molins et al patent has an unusual end flap structure. The structure cannot be made by current cigarette packaging equipment. Additionally, the easy opening pre-perforated feature of this inner liner can result in severing of the foil layer thus reducing the barrier properties of the laminate.
It would be desirable to provide barrier sealed cigarette packages which can be manufactured using current cigarette packaging equipment or modified version thereof. Additionally, it would be desirable to provide a barrier package of cigarettes or other smoking articles which could be manufactured, i.e., folded and heat sealed, at rates approaching or equal to contemporary rates of cigarette package production. Additionally, it would be desirable to provide barrier sealed cigarette packaging having an appearance comparable to current cigarette packages and having outstanding barrier properties.